This invention relates to magnetic apparatus adapted for inducing magnetic fanning of steel sheets for purposes of efficient manual handling.
Sheet steel is commonly stored in a stacked configuration upon a horizontally oriented work table or storage rack. Where, for example, rectangular sheets of one-eighth inch steel are stored in a stacked configuration, such sheets are commonly used in sequence from the top down. Where such sheets are neatly stacked one upon the other, the topmost sheet offers no surface which may be conveniently manually grasped to effectuate removal from the stack. Such stacked sheets of steel are often resistant to sliding, preventing a worker from exposing an edge over a side of the stack for grasping. Also, oil which is commonly disposed between such stacked sheets often results in cohesion creating further resistance to removal of a single sheet from the stack. Such cohesion effectively sticks together the sheets.
Stacks of sheet steel are known to become temporarily magnetized upon exposure to a magnetic field. Where the magnetic lines of flux from a magnetic field cross the striations of a stack of sheet steel, the individual sheets are magnetized in a manner causing their broad faces to form a series of magnetic poles. Where such magnetization occurs, consistent orientation of the magnetic poles causes opposing poles to be in contact with each other, adhering the layers of sheet steel together. Conversely, where lines of magnetic flux are caused to pass horizontally through stacked sheet steel, the induced magnetic poles are located at the edges of the sheets of steel. Consistent orientation of such induced magnetic poles causes like poles to be grouped together at the edges of the stack, resulting in magnetic repulsion. Such magnetic repulsion at the edges of the sheet steel stack upwardly fans the stack, separating adhered sheets from each other, and exposing individual edges for convenient grasping. Magnetic mechanisms adapted for accomplishing such magnetic fanning of stacks of sheet steel are known.
One such known magnetic mechanism incorporates an electromagnet which may be conveniently placed in operating proximity with a stack of sheet steel. The electromagnet may be turned on for magnetic fanning of the sheets, and may be conveniently be turned off when no longer needed. However, the coiled windings of such mechanisms are undesirably bulky, and such mechanisms undesirably require an electrical power supply.
Magnetic fanning mechanisms incorporating permanent magnets are similarly known, such mechanisms overcoming some of the undesirable characteristics of electromagnets. However, permanent magnets may not be switched on and off in the manner of electromagnets. Therefore, where a permanent magnet sheet fanner is utilized, its magnet must be forcefully pulled away from the stack of sheets when not in use. Strong magnetic attraction between a magnetic fanner incorporating permanent magnets and sheet metal typically makes it difficult to pull the fanning mechanism away from sheet metal when not in use.
The instant invention ameliorates or lessens the difficulty of pulling such magnets away from stacked sheet steel by providing structures adapted for rotating or pivoting a permanent magnet assembly away from the stacked sheet steel rather than directly forcing or driving the magnet linearly away from the sheet steel stack. By providing structure for pivoting the magnets toward and away from the stacked sheet steel the inventive sheet fanner incorporates a novel, inventive and useful xe2x80x9con-offxe2x80x9d function.
The instant inventive magnetic sheet fanner comprises four core structural elements: a housing or support frame, a permanent magnet assembly, pivotal or rotatable mounting means, and turning means; the housing supporting each of the other three structural elements.
The housing primarily functions as a support frame member. Ideally, the housing forms an occlusive closure, protecting supported structures from dirt and debris. Suitably though less desirably, the housing may be configured as an open frame. Preferably, the housing has a sheet contact side configured as a vertically elongated bearing face. The vertical length of the bearing face typically is equal to or greater than the maximum height of sheet metal stacks to be fanned by the magnetic sheet fanner. For example, where the magnetic sheet fanner is to be utilized for fanning sheet metal stacked ten inches high, the vertical dimension of the bearing face should be at least twelve inches. Suitably, such vertical length may be less than such maximum height where means are provided for alternately upwardly and downwardly positioning the magnetic sheet fanner with respect to stacked sheet steel.
The vertically elongated bearing face of the housing comprises the structure through which magnetic flux emanates for fanning a stack of sheet steel. It is preferable for the bearing face to be composed of non-magnetic steel so that the thickness of the face provides an xe2x80x9cair gapxe2x80x9d between the sheet stack and the magnet; such gap lessening the force needed to pivot the magnet away from the sheet stack. Where magnetic flux from opposing poles emanates through the bearing face, the non-magnetic character of the bearing face additionally functions to avoid a magnetic armature across the magnetic poles, which may undesirably reduce the strength of the magnetic field available for fanning sheet steel. Where the bearing face comprises magnetic steel, avoidance of such magnetic armature effect may be suitably achieved by configuring such face as vertically oriented strips or plates, which are spaced apart from each other; the space providing an air gap between the strips or plates. Preferably, the outer surface of the vertically elongated bearing face has a plurality of vertically oriented slide ridges for reducing frictional forces between the sheet steel and the magnetic sheet fanner.
The permanent magnet of the instant inventive magnetic sheet fanner is preferably situated within the housing immediately behind the vertically elongated bearing face. Preferably, the poles of the permanent magnet are vertically elongated allowing them to be mounted co-extensively along the inner surface of the bearing face. Where it is desirable to expose the bearing face to magnetic flux from opposing poles, the permanent magnet is preferably configured as a vertically elongated horseshoe magnet. Preferably the axes of magnetization at the poles of such magnet are parallel to each other. Suitably, though less desirably, such axes may be oriented at an angle to each other. A preferred means of constructing such vertically elongated horseshoe magnet incorporates a vertically elongated mild magnetic steel back plate upon which dual rows of block shaped bar magnets are fixedly mounted. The magnets in each row are consistently arranged so that the magnets in one row forwardly expose their south poles, while the magnets in the other row forwardly expose their north poles. Such arrangement allows the mild magnetic steel back plate to serve as an armaturing link between the rearwardly exposed north and south poles of the bar magnets, causing the combination of the bar magnets and the back plate to form the vertically elongated horseshoe magnet.
In a suitable alternate configuration of the permanent magnet, similar block-shaped bar magnets are arranged in a single vertical row along a backing plate, cumulatively forming at least a first vertically elongated bar magnet. The block shaped bar magnets are preferably consistently oriented with their north (or alternately south) poles facing forwardly from the back plate. Where the back plate serves as a mounting surface for a single row of permanent bar magnets, such back plate is preferably composed of a ferrous material such as mild steel to aid in redirecting the rearwardly oriented field toward a stack of sheet steel.
In each permanent magnet configuration described above, the pivotal or rotatable mounting means element allows the permanent magnet to pivotally or rotatably move between first and second positions within the housing, such pivotal motion providing an xe2x80x9con-offxe2x80x9d function. While the permanent magnet occupies the first xe2x80x9conxe2x80x9d position, magnetic flux emanating from its forwardly facing pole or poles is directed through the vertically elongated bearing face, and into stacked sheet metal, fanning the sheet metal. Upon pivoting or rotating movement of the permanent magnet to its second position, such magnetic flux is redirected away from the sheet metal, effectively xe2x80x9cturning offxe2x80x9d the magnetic sheet fanner, by greatly reducing magnetic attraction to the stack. Upon such pivoting or rotating movement, the stacked sheets are allowed to return to their original non-fanned condition.
In order to accomplish such pivoting or rotating motion, the pivoting or rotatable mounting means preferably comprises a vertically oriented axle fixedly mounted upon the rearward surface of the back plate, the upper and lower ends of the axle respectively extending upwardly and downwardly from the upper and lower ends of the back plate. Such upward and downward extensions conveniently serve as journals. Alternately, the axle may be non-continuous along the rearward surface of the back plate, so long as the upper and lower journal extensions are rigidly mounted. Also, alternately and suitably, the upper and lower ends of the back plate itself may be milled to form upper and lower journals, allowing the back plate to dually function as a mounting surface and as a pivoting or rotating means. Other pivoting means may be suitably utilized.
In order to facilitate pivotal or rotatable motion of the permanent magnets about such upper and lower journals, upper and lower bearings for receiving said journals are necessarily fixedly mounted within the housing. Preferably, the lower bearing is fixedly mounted upon and supported by a floor of the housing. Also preferably, the upper bearing is fixedly mounted upon a ceiling or upper wall within the housing, such upper wall overlying the permanent magnet. Suitably, the upper and lower bearings may be fixedly mounted upon other structures within the housing such as bearing supporting brackets.
The orientations of the upper and lower journals and the upper and lower bearings preferably vary in accordance with the configuration of the permanent magnet. Where the permanent magnet is configured as a vertically elongated horseshoe, it is preferable to orient the journals and bearings within the housing to allow the permanent magnet to swing in the manner of a door along a 90xc2x0 arc. Such motion is preferably accomplished by plate and by similarly laterally offsetting the bearings with respect to the midline of the vertically elongated bearing face.
Where the permanent magnet is configured as a vertically elongated bar magnet, the journals are preferably located rearward of the midline of the vertically elongated north or south pole, allowing such pole to rotate in a circular path about the journals. In such configuration, the upper and lower bearings are preferably centrally located within the housing. In such configuration, the proximity of the upper and lower bearings with respect to the bearing face is preferably closely fitted to minimize the distance between the forward facing pole of the permanent magnet and the inner surface of the bearing face while such magnet is in its first xe2x80x9conxe2x80x9d position, while leaving such magnet free to swing in an arc across the interior of such surface. In such configuration, upon rotation of the permanent magnet 180xc2x0 away from its first xe2x80x9conxe2x80x9d position, the pole face in closest proximity to the bearing face is rotatably moved rearwardly within the housing. Preferably, the position of the magnet and backing plate in relation to the journals is adjusted to achieve a sufficient reduction in magnetic flux emanating through the bearing face upon a 180xc2x0 rotation, and to achieve acceptable compactness of the housing.
The housing walls other than the bearing face preferably comprise mild magnetic steel. Utilization of mild magnet steel for the housing functions to act as an armaturing link between the north and south poles of the bar or horseshoe magnet upon positioning in their off positions. By acting as an armaturing link in the off position, the mild magnetic steel walls reduce magnetic flux which emanates from the sheet fanner while not in use.
The turning means element of the inventive magnetic sheet fanner comprises some suitable structure adapted to apply torque to the permanent magnet assembly, rotating or pivoting the assembly away from its first xe2x80x9conxe2x80x9d position. In a preferred torquing or turning means configuration, an upper end of the upper journal is exposed through the upper bearing, providing a convenient point for application of torque to the journal. Application of torque to such journal utilizes the journal as a drive axle. Any one of numerous means of applying torque to such exposed journal end may be suitably utilized. For example, a manually operated turn wheel may be axially mounted upon said journal end. Similarly, a crank handle may be mounted upon said journal end. Also suitably, the power output shaft of an hydraulic motor or electric servo-motor may be directly linked to said journal end. Suitably, the lower end of the lower journal may be exposed, allowing similar torque applicating means to be applied to the lower journal.
Suitably, though less desirably, the torque applying means may be directed to some other portion of the permanent magnet, backing plate, axle and journal assembly, rotating the permanent magnets about the journals, without utilizing either of the journals as a drive axle.
A preferred means of applying torque to the preferred exposed upper journal is to fixedly mount a lever arm upon said journal, and to articulate such lever arm through the action of a telescoping shaft of a pneumatic cylinder. In such preferred assembly, the base of the pneumatic cylinder is preferably fixedly and pivotally mounted within a laterally extending upper chamber of the housing. The telescoping shaft of such cylinder is preferably pivotally mounted upon the distal end of the lever arm causing the piston, telescoping shaft, and lever arm combination form a conventional piston and crankshaft assembly. Suitably, a hydraulic cylinder may be utilized in place of the pneumatic cylinder. Also suitably, various motor operated or manually operated jack screws may be utilized.
An alternate preferred means of applying torque to the preferred exposed upper journal end incorporates a first drive pulley or sprocket fixedly mounted upon said journal end. Such first drive pulley or sprocket is preferably rotatably driven by a drive belt or chain, such belt or chain preferably being driven by a second drive pulley or sprocket of a pneumatic rotary actuator.
Preferably, the housing encases the permanent magnet, the pivotal or rotatable mounting means, and encases the turning means, the housing forming a substantially occlusive closure preventing dirt and debris from fowling internal mechanisms. Also preferably, an external surface of the housing is configured as a mounting plate for mounting the sheet fanner upon a sheet metal storage table or upon a mobile rollable cart.
Accordingly, it is an object of the present invention to provide a magnetic sheet fanner incorporating means for pivotal or rotatable mounting of a permanent magnet within a housing, such means providing an xe2x80x9con-offxe2x80x9d function.
It is a further object of the present invention to provide such a sheet fanner incorporating turning means for pivoting or rotating the permanent magnet within the housing.
Other and further objects, benefits, and advantages of the present invention will become known to those skilled in the art upon review of the Detailed Description which follows, and upon review of the appended drawings.